ABSTRACT:- The spectrum which is used by telecom companies for radio communications is a natural resource. With the emergence of new electronic devices, the unlicensed spectrum becomes increasingly scarce. Even though the licensed spectrum are allocated to certain services, it is being reported by FCC and other regulating bodies that large portions of the allocated frequency bands are partially occupied, leaving holes in between and hence leading to inefficient overall spectrum utilization. Opportunistic access of spectrum bands through dynamic allocation have emerged as potential enablers of more efficient use of various resources in future wireless communications. Dynamic allocation allow secondary users (unlicensed) to occupy or use the gaps (free band) when the primary users (licensed) do not use the spectrum. These systems have the capabilities of obtaining knowledge of their operating environment and internal state using which these systems can optimize their performance and increase effective spectrum utilization. A multi-hop self-organized and dynamic network with intelligent learning and cognitive capabilities at few of its nodes. Most of the research on CRNs has focused on Physical and MAC layer issues. The prototype addresses the issues in PHY/MAC layers and also the performance issues at Network layer that includes service prioritization at different traffic types in the presence of node mobility, dynamic channel selection, and multipath routing to ensure quality multimedia delivery to the users at remote places and rural schools.
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